Our universe observes the birth and death of millions if not billions of stars, every minute. When a star, almost 10 times the size of our sun, runs out of its fuel, and the fusion reaction at the core of it stops, a ton of hot gasses collapse on the core rapidly. Unable to accommodate the astronomical amount of mass into a tiny core, a massive explosion takes place, releasing so much energy that the outer layers of the stars are violently thrown into space. This phenomenon is known as a super nova.
If the collapsing core of the star, has a stellar mass between 1 and 3 times that of our sun, then it wouldn’t have further gravitational collapse. It becomes a neutron star. If the collapsing star has a mass higher than 20 times that of our sun it turns into a black hole. And if the mass is less than 8 times, then it turns into a white dwarf. More on that in a separate video.
The neutron stars are usually just the size of a small city. Don’t be fooled though, the density of this stellar object is so high that if hypothetically, you took out a sugar cube sized chunk of its mass, it would weigh as much as a mountain on earth. Only if you could get near one, before being fried up by the radiations.
Warning! This part of the video deals with a bit of physics. When a star collapses, and forms a neutron star, the speed at which the star spins, increases. This is also known as conservation of angular momentum. this can be explained with a simple example. If you have ever seen a gymnast spinning on a pole, the speed at which he is spinning becomes faster when he pulls his legs in towards his stomach. The Same happens with stellar bodies.
Stars spin at a pretty fast rate. for example, our sun completes a rotation in about 25 days. Most neutron stars complete a full rotation in a second. But sometimes, they could spin so fast, that in one second, they could complete hundreds of rotations.
Every star has a magnetic field. So in the neutron star phase, along with the mass, the magnetic field is also compressed. Which makes the field stronger at a close range. Along with the super fast spin of the star, the concentrated magnetic field too, moves at the same speed. This produces radio waves, which are shot out from the magnetic north and south poles of the neutron star, into space.
Since neutron stars are so small, detecting them becomes nearly impossible. Unless the beams of radio waves which they emit, directly hit the earth and are picked up by the radio telescopes present on the ground.
Like we mentioned before, that neutron stars rotate at a pretty fast speed, the direction of beam keeps changing. As a result, the beams of radio waves received on earth are not steady but pulsating. And that is where it gets its name from- Pulsars.
Scientists estimate the milky way galaxy to have about a billion neutron stars, out of which only a little over 2000 pulsars, have been detected.Here’s a fun fact. The radio waves which are received from a pulsar are a stable source of consistent interval pulses. So, these pulses can be compared to atomic clocks and can serve as a stellar time keeper.
That’s all for today. Come back again, cause we will upload more videos explaining other stellar phenomenons. If you’ve learned something from this video makes sure to hit like and share. Subscribe to explified cause that keeps us motivated to upload more content . See you soon.